There is a point at which the benefits of corporate knowledge sharing exceed the costs. This point varies with the nature of the company and its business.

Costs:
Risk of theft of data,
Risk of destruction of data,
Risk of misuse of data,
Risk of violation of customer confidentiality,
Risk of violation of intellectual property rules,
...

Benefits:
Higher quality decision-making,
Greater adaptability to changing environment,
Broader base of knowledge sources,
...